Moniliophthora atlantica N. A. Ramirez & Niveiro, sp. nov

Index Fungorum number: IF 555944; Mycobank number: MB 555944; Facesoffungi number: FoF 10838; Figs. 1, 2

Etymology – referring to the ecoregion where the species was collected, the Atlantic Forest.

Holotype – OS17-2–7 (CTES 0568284).

Pileus 3–20 mm in diam, circular, convex to broadly convex when mature, some subumbonated, slightly depressed at center, surface pale red (7A3-8A3), pastel red (7A4-8A4), dull red (8B4-8C4) to greyish red (8B5-8C5), usually darker near the center, reddish brown (8D7-8E6-7); surface fibrillose to pubescent, dry, opaque, not hygrophanous, sulcatestriate; margin incurved to plane. Context thin (<1 mm), membranaceous, yellowish white (1A2), odor and taste not tested. Lamellae free to slightly adnexed, subdistant, regular, sometimes furcate towards the margin and with intervenose, lamellulae in 2–3 series, yellowish white (1A2) to pale yellow (1A3), smooth margin, concolorous with sides. Stipe 2–12×0.8–2 mm, central, sometimes slightly lateral, cylindrical, equal or slightly thinner towards the middle, hollow, insititious, apex concolorous with lamellae, yellowish white (4A2), turning pale orange (6A4-6B4) towards the middle of the stipe, darkening towards the base, reddish brown (9E6-7) to dark brown (9F6-8), surface fibrillose, pubescent under lens, more distinctive toward the base. Spore-print not observed, presumably yellowish white (1A2). KOH and NaOH reactions on pileus surface negative.

Basidiospores (7–)8.2–11.1×4.5–6.2(–7.2) µm, x̅=9.4±0.77×5.6±0.4 5 µm, Q =1.4–2.1, Qx=1.7±0.12, n=25, N =2, ellipsoidal to oblong, amygdaliform in lateral view, with a slight suprahilar depression, thin-walled, smooth, hyaline, inamyloid, without germ-pore. Basidia 34.7–50×7.5–9 μm, clavate to narrowly clavate, 4-spored, thin-walled. Basidioles 22.2–34 × 4–7.7 μm, clavate, thin-walled, abundant. Pleurocystidia absent. Cheilocystidia 18–33.2×2.5–6.4 μm, subcylindrical to narrowly clavate, sometimes with a fingerlike apical protuberance, rounded apex, thin-walled, hyaline. Hymenophoral trama subregular, composed of cylindrical
interwoven hyphae, up to 7 μm in diam, thin-walled, hyaline. Pileipellis a cutis of repent, more or less interwoven cylindrical hyphae, up to 8 μm broad, thin-walled, smooth, hyaline, inamyloid, covered by clusters of dextrinoid hairs. Hairs of the pileus surface 50–315×4–8.5 μm, setiform, acicular, thick-walled, up to 3 μm broad, dextrinoid, sometimes with secondary septa, rounded apex, KOH– (do not turn olive green). Stipitipellis a cutis of repent hyphae, up to 8 µm in diam, parallel, elongated, dextrinoid. Hairs of the stipe surface 20.1–44.1×4.4–8.3 μm, setiform, similar to hairs of the pileus surface, thick-walled, up to 2 μm broad,
dextrinoid, more abundant in young specimens. Clamp connections presents.

Habitat and distribution – Marasmioid, growing on small freshly fallen branches of unidentified dicots and stems of living lianas. In Misiones Province, Argentina.

Material examined – Argentina, Misiones, San Ignacio, Osununú Private Reserve, 27°17′09.3″ S, 055°34′03.6″ O, 206 m asl, on recently fallen branches, 30 September 2018, on recently fallen branches leg. Ramirez N. et al., OS17- 2–7 (CTES 0568284, holotype), OS18-2–5 (CTES); ibid., Teyú Cuaré Provincial Park, 27°17′05.5″ S, 055°35′21.1″ O, 177 m asl, on living liana, 1 October 2018, leg. Ramirez N. et al., TC19-2–1 (CTES); Iguazú, Iguazú National Park, 25°43′29.2″ S, 054°28′08.6″ O, 239 m asl, 2 October 2018, leg. Ramirez N. et al., IG16-3–11 (CTES); ibid., Palmital, 25°41′19.7″ S, 054°28′26.3″ O, 186 m asl, 13 October 2017, leg. Ramirez N. et al., IG10-1–1 (CTES).

GenBank numbers – OS17-2–7: ITS=ON180675; IG16-3–11: ITS=ON180677.

Notes – The matrix included 35 sequences belonging to 20 taxa of Moniliophthora and related genera, such as Crinipellis, Chaetocalathus and Marasmius. A Tetrapyrgos nigripes sequence was used to root the tree (Kropp and Albee-Scott 2012). The alignment resulted in a total of 602 characters, of which 367 were conserved sites, 235 variables and 150 parsimony-informative. The best substitution models were estimated as TPM2uf+ G, K80, and SYM + G for ITS1, 5.8S, and ITS2 respectively. Since the Maximum Likelihood and Bayesian Inference analysis yielded trees with similar topology, only the latter is shown in which the support values of PP/BS for the compatible nodes between them (Fig. 3). In the phylogeny, two main clades are observed, although without statistical support: Chaetocalathus, which groups all species of this genera included, and the clade Moniliphthora/Crinipellis. Within the latter, M. atlantica, the new species proposed here, forms a well-supported clade (0.99/100) as sister group to M. perniciosa (1/98).

Figure 1 – Moniliophthora atlantica, general aspect, lamellae and stipe. a, b TC17-2–7 (holotype). c, d OS18-2–5. e TC19-2–1. f IG16-3–11. Scale bars: 20 mm

Figure 2 – Moniliophthora atlantica microscopic characters. A Basidiospores. B Basidia. C Cheilocystidia. D Caulocystidia. E Pileipellis elements. Scale bars: 10 μm

Figure 3 – Bayesian Inference Analysis based on ITS sequences of Moniliophthora and related genera. The sequences obtained in this work are indicated in blue, type material in bold. Support values, when present, consist of the posterior probability (PP) followed by the bootstrap (BS), separated by a /. Only nodes with support above 50% were scored, and support values greater than 0.90/70 are showed (- indicates a lower value)